The instant invention relates to an error detection and display device. The inventive device is especially useful for detecting and displaying malfunctions in certain operating systems of wheeled vehicles.
A known testing and display device of this type is used in passenger cars to test an anti-lock braking (ABS) system. A starting and ignition device of the vehicle serves as a switch-on control producing signals to switch on the testing and display system during or immediately after engine ignition. In this known system, a warning light, which serves as the display component of the system, goes on after ignition of the engine and the testing device goes through cyclical verification cycles to test certain components (e.g. cables, plugs, sensors, electronics, solenoid valves) and functions. When a first defined verification cycle of the testing device has been completed and no error has been detected, the warning light is switched off. This occurs relatively quickly so that this verification is usually completed while the vehicle is still standing still. In this manner, rapid and simple verification of the ABS system is achieved even before the beginning of car movement. However, if an error is detected, the warning light stays on, as is also the case when errors are detected during vehicle travel.
It is to be noted that some errors of the above-mentioned components and functions cannot be detected during a first operating state of the vehicle which is that of the vehicle at a standstill. Such errors, which may be referred to as dynamic errors, can only occur and can only be detected when the vehicle has reached a predetermined minimum speed or when the wheels rotate at a minimum rotational speed on a testing stand, i.e., in a second operating state of the vehicle. Error signals produced by rotational-speed sensors mounted on the wheels or on an axle of vehicle are examples of these dynamic errors which occur only during the second operating state of the vehicle, considered to be the vehicle travelling above a predetermined minimum speed.
Since the described verification procedure for an anti-lock braking system is carried out immediately after starting the vehicle engine and while the vehicle is at a standstill, only those errors which occur and can be detected during this first operating state can be displayed, i.e., by keeping the warning light on. Such errors may be referred to as errors of the first kind. Dynamic errors, i.e., errors of the second kind which occur and can be detected only in the second operating state of travel of the vehicle at above the predetermined minimum speed, are at first not taken into consideration in the described testing of the vehicle.
A testing system is also known for commercial vehicles in which the verification of an anti-lock braking system and thereby the lighting of the warning light is extended until the above-mentioned second state of vehicle operation is reached, i.e , until a minimum speed has been reached and dynamic errors can be measured. In this manner, it is possible to carry out a verification of the rotational-speed sensors as early as in the start-up phase of the commercial vehicle so that the driver is alerted in time of possible dynamic errors, such as rotational-speed sensor errors or errors of the rotational-speed sensor signals. With this latter type of testing device, the driver must therefore first set the utility vehicle in motion before the warning light will be switched off if no error is detected As a result of this, the warning light remains on for a relatively long period of time.
It is the object of the instant invention to provide an error detection and display system which is especially useful for a vehicle such that the detection and display of possible errors occurring only in a second state of operation and which can only be detected in that state (e.g., dynamic errors) may be detected while the vehicle is in a first state of operation (e.g., while the vehicle is still at a standstill).